Oct. 19, 2014
UAV being prepared for zip-line testing
Small unmanned aerial vehicles (UAVs) are extremely flexible devices, and can often used in aerial surveys, photography and environmental monitoring. But most of the designs are expensive and time-consuming to produce. In March this year engineers in The University of Sheffield Advanced Manufacturing Research Centre (AMRC) with Boeing's new Design & Prototyping Group designed and prototyped an innovative small unmanned aircraft using advanced design tools and 3D printing technology.
The airframe parts were all printed using a fused deposition modelling (FDM) technology on a Stratasys Fortus 900mc FDM 3D printer. To save material cost and building time, the AMRC team designed each part of the structure specifically for additive manufacture so that it can be printed without any need for support material. The finished aircraft has a wingspan of 1.5 metres, weighs under 2kg, and can be easily split into two halves around the central spine for easy transport.
Members of the AMRC Design and Prototyping GroupUAV team, left to right Sam Bull, Mark Cocking, Keith Colton, Daniel Tomlinson, John Mann and Garth Nicholson.
Now the team has taken another step forward: they have developed their original glider to incorporate electric-powered, ducted fan engines and unveiled the new developments at a top US aerospace conference.
To create this latest version of the UAV, the team used 3D printing to produce carbon fibre components and make component jigs, fixtures and moulds, as well as parts of the UAV's airframe.
One of the aerodynamic modifications to the glider concept was the inclusion of more wing twist (washout). Since any asymmetry would result in difficulty trimming for level flight over the predicted speed range, the parts have to be printed and assembled accurately. To achieve it, the printed wing root and tip ribs, intermediate carbon ribs, and main spars were designed to self-jig to the upper and lower skins. Structural adhesive was use to bond the parts together.
Wing structure with top skins ready for assembly
The central body of the UAV is complete with the twin engine ducts and complex internal features which drive this device at nearly 20 metres a second, or almost 45 miles an hour. Designers also improved pitch control by creating a moveable "Duck Tail" that collects the air leaving the UAV's engines for aerodynamic effect, using concepts similar to those recently used in Formula One.
These add-ons have turned their 2kg glider into a 3.5kg powered UAV. Due to the increased weight and higher projected flying speeds of the powered version compared with the glider, a catapult launch was deemed necessary. So they also designed a launch catapult, using 3D printed parts. The concept featured an automatic release mechanism which locked the UAV onto the carriage, allowing the motors to run at full power before launch. The catapult is capable of propelling the UAV into the air with an acceleration up to three times that of gravity, achieving a launch speed of 12 metres a second or just under 30 miles an hour.
They don't plan to stop there. Their next challenge will be to replace the electric ducted fans with miniature gas turbine engines and seeking to double the UAV's wingspan to three meters. They are also looking to employing vapour polishing for finishing some printed components and developing structural batteries made from carbon composites.
Dr Garth Nicholson, Senior design engineer said: "The project was a success on all levels, from team building, experience gained in structural and systems design and design for manufacture through to testing and validation of Computational Fluid Dynamics.
"The aircraft was developed using both an incremental design philosophy, as well as trialling experimental manufacturing techniques in carbon fibre production".
The project showcases the Group's skills and technological capabilities. Particularly the new techniques that rapidly reduced the time, the amount of materials and the cost of manufacturing components using 3D printing technology could help small and medium-sized manufacturers to develop new products and move into new markets.
The team says they will also build more sophisticated electronic control systems and GPS into the airframe. The ultimate project goal is the design of a 3 metre span autonomous UAV, designed and built using advanced manufacturing techniques.
Check out this video of assembly and test of this powered UAV based on a FDM-printed airframe.
Source: ARMC paper
Posted in 3D Printing Applications
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Thats amazing guys. Cant wait to see what you do next!
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